1. Field of Invention
Embodiments of the present invention relate generally to phase-changeable memory devices and methods of manufacturing phase-changeable memory devices. More particularly, the embodiments of the present invention relate to a phase-changeable memory device employing a phase-changeable material and a method of manufacturing the phase-changeable memory device.
2. Description of the Related Art
Typically, a phase-changeable structure includes a lower electrode, a phase-changeable layer pattern and an tipper electrode. The phase-changeable layer pattern is located between the lower electrode and the upper electrode. The phase-changeable layer pattern may include a chalcogenide. When a current generated by a difference in voltage between the lower electrode and the upper electrode is provided to the phase-changeable layer pattern, a phase of the phase-changeable layer pattern may be changed from a single crystalline phase having a relatively low resistance into an amorphous phase having a relatively high resistance. In addition, when the current provided to the phase-changeable layer pattern is removed or reduced by a predetermined amount, the phase of the phase-changeable layer pattern may be changed from the amorphous phase into the single crystalline phase.
The phase-changeable structure including the lower electrode, the phase-changeable layer pattern and the upper electrode may be used as a variable resistance because the phase of the phase-changeable layer pattern may vary.
In a conventional method of manufacturing a phase-changeable structure, a metal nitride layer is formed on a phase-changeable layer after the phase-changeable layer is initially formed on a lower electrode. An etching process is then performed on the metal nitride layer and the phase-changeable layer so that an upper electrode and a phase-changeable layer pattern may be formed.
However, when the upper electrode and the phase-changeable layer pattern are formed by the etching process, an etching material may chemically react with the phase-changeable layer, thereby damaging the phase-changeable layer. As phase-changeable structures become smaller, damage due to etching processes becomes more serious.